GlobalDump is a relatively simply addon designed to dump the _G table recursively into its saved variable, GlobalDump_saved.
GlobalDump was designed to aid in comparing the API from one version of WoW to another. Doing this requires copying the SavedVariables file after dumping one of them, as you're probably aware.
After dumping both "old" and "new" versions, you can use the compare feature to populate the compare table with any new/changed data. (Will not detect changes to functions or userdata)
GlobalDump is in relative infancy and may not work completely, but it does the dump and compare jobs well, as far as I can tell.
GlobalDump is probably best used with an otherwise nearly clean Interface folder, and a fresh WTF folder, on a new character.
I recommend use with Addon Control Panel and Lua Browser.
I used Lua Browser to view the compare table somewhat easily. I'm sure there are other ways, but this was simply the way I found easiest. (Let me know if you have suggestions for a different method!)
/globaldump - Prints out commands
/globaldump old - Dumps to GlobalDump_saved.old
/globaldump new - Dumps to GlobalDump_saved.new
/globaldump compare - Compares .old and .new, dumping to GlobalDump_saved.compare
/globaldump reverse - Switches .old and .new